Coated articles are known in the art for use in window applications such as insulating glass (IG) window units, vehicle windows, monolithic windows, and/or the like. In certain example instances, designers of coated articles often strive for a combination of high visible transmission, desirable color, low emissivity (or emittance), low sheet resistance (Rs), and/or low U-values in the context of IG window units. High visible transmission and desired coloration may permit coated articles to be used in applications where these characteristics are desired such as in IG or vehicle window applications, whereas low emissivity and low sheet resistance permit such coated articles to block significant amounts of IR radiation so as to reduce for example undesirable heating of vehicle or building interiors.
Low-E coatings are typically deposited on a glass substrate by sputtering. Emissivity and/or sheet resistance values of a coating or coated article are driven in large part by the IR reflecting layer(s) which is/are typically made of silver or the like. However, it has been difficult to achieve low tolerance variation with respect to emissivity values of such coatings. In other words, a problem in the art has been difficulty in achieving a desired low emissivity value and/or sheet resistance value within a given small tolerance variation. The tolerance variation has been larger than desired.
In view of the above, it will be appreciated that there exists a need in the art for a coated article including a low-E coating that is designed so that a desired low emissivity value can be achieved within a given small tolerance range (e.g., a tolerance of plus/minus 1%). It would also be desirable to provide such a coating that also achieves one or more of: high visible transmission, low emissivity, thermal stability upon optional heat treatment such as thermal tempering, a low U-value, and desirable coloration and/or reflectivity values.
In certain example embodiments of this invention, it has surprisingly been found that the provision of a layer of or including zirconium silicon oxynitride in the lower dielectric portion of the coating, between the glass substrate and the IR reflecting layer (e.g., of silver or the like) unexpectedly improves the quality of the IR reflecting layer thereby permitting the coated article to realized low emissivity values with low tolerance variations. Providing zirconium silicon oxynitride under a layer of or including zinc stannate and under a layer of or including zinc oxide, in the lower dielectric portion of the coating, has surprisingly been found to improve the quality of the silver and thus lower emissivity values and lower emissivity tolerance values in a desirable manner. Even though the zirconium silicon oxynitride is not directly contacting the IR reflecting layer, it still surprisingly improves the quality of the overlying IR reflecting layer thereby permitting thermal properties of the coating to be improved and manufactured in a more consistent manner. The IR reflecting layer has been found to grow better and have a smoother base which can more easily be repeated on a consistent basis. It has also been surprisingly found that the provision of a layer of or including titanium oxide (e.g., TiO2) over the zirconium silicon oxynitride unexpectedly results in an increase in visible transmission of the coated article and improved optical properties, as well as an increase in line speed.
In certain example embodiments of this invention, there is provided a coated article including a coating supported by a glass substrate, the coating comprising moving away from the glass substrate: a dielectric layer comprising zirconium silicon oxynitride; a layer comprising titanium oxide; a layer comprising zinc stannate; a layer comprising zinc oxide located over and directly contacting the layer comprising zinc stannate; an infrared (IR) reflecting layer comprising silver located on the substrate over and directly contacting the layer comprising zinc oxide; and a layer comprising metal oxide located over at least the IR reflecting layer comprising silver; wherein the coating contains only one silver based IR reflecting layer; wherein the coating has a normal emissivity (En) of no greater than 7%, and measured monolithically the coated article has a visible transmission of at least 75%.
In certain example embodiments of this invention there is provided a coated article including a coating supported by a glass substrate, the coating comprising moving away from the glass substrate: a dielectric layer comprising zirconium silicon oxynitride; a layer comprising zinc stannate; a layer comprising zinc oxide located over and directly contacting the layer comprising zinc stannate; an infrared (IR) reflecting layer comprising silver located on the substrate over and directly contacting the layer comprising zinc oxide; and a layer comprising metal oxide located over at least the IR reflecting layer comprising silver; wherein the layer comprising zirconium silicon oxynitride contains at least three times as much nitrogen as oxygen, and wherein a ratio of Zr/Si (atomic) is from 0.30 to 0.47 in the layer comprising zirconium silicon oxynitride.
In certain example embodiments of this invention, there is provided an IG window unit comprising: first and second glass substrates with a gap therebetween; a coating supported by the second glass substrate and facing the gap, the second glass substrate to be located closer to a building interior than is the first glass substrate, the coating comprising moving away from the second glass substrate: a dielectric layer comprising zirconium silicon oxynitride; a layer comprising titanium oxide; a layer comprising zinc stannate; a layer comprising zinc oxide located over and directly contacting the layer comprising zinc stannate; an infrared (IR) reflecting layer comprising silver located on the substrate over and directly contacting the layer comprising zinc oxide; and a layer comprising metal oxide located over at least the IR reflecting layer comprising silver; wherein the coating contains only one silver based IR reflecting layer; wherein the coating has a normal emissivity (En) of no greater than 7%; wherein the IG window unit has a visible transmission of at least 70% and a U-value of no greater than 1.4.